There are many popular applications that provide maps of outdoor areas. Mapping programs such as Google Maps™ indicate, for example, the location of city streets or buildings. It would also be desirable to have applications for mapping indoor locations e.g., the interior floorplan of a building such as a mall or library. Since there are a huge variety of indoor environments, it would be particularly useful if an accurate map of an indoor area could be automatically generated e.g., based on the movements of mobile devices, which are carried by users who are traversing the area. However, developing such a system is challenging. For example, some approaches involve using a system referred to as Pedestrian Dead Reckoning (PDR). In PDR, a mobile device tracks the distance that a device has traveled and any changes in direction that the device has undertaken. A map can then be created based on the directional and distance changes recorded by the mobile device. However, mobile devices are often not able to perfectly record such changes, which result in errors that grow exponentially over time. Accordingly, there are ongoing efforts to further improve the accuracy of indoor mapping systems.